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bpf: libbpf: Add btf_line_info support to libbpf 

This patch adds bpf_line_info support to libbpf:
1) Parsing the line_info sec from ".BTF.ext"
2) Relocating the line_info.  If the main prog *_info relocation
   fails, it will ignore the remaining subprog line_info and continue.
   If the subprog *_info relocation fails, it will bail out.
3) BPF_PROG_LOAD a prog with line_info

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau 2018-12-07 16:42:31 -08:00 committed by Alexei Starovoitov
parent f0187f0b17
commit 3d65014146
5 changed files with 238 additions and 88 deletions
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82
tools/lib/bpf/bpf.c
View File

@ -173,11 +173,36 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,
-1);
}
static void *
alloc_zero_tailing_info(const void *orecord, __u32 cnt,
__u32 actual_rec_size, __u32 expected_rec_size)
{
__u64 info_len = actual_rec_size * cnt;
void *info, *nrecord;
int i;
info = malloc(info_len);
if (!info)
return NULL;
/* zero out bytes kernel does not understand */
nrecord = info;
for (i = 0; i < cnt; i++) {
memcpy(nrecord, orecord, expected_rec_size);
memset(nrecord + expected_rec_size, 0,
actual_rec_size - expected_rec_size);
orecord += actual_rec_size;
nrecord += actual_rec_size;
}
return info;
}
int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
char *log_buf, size_t log_buf_sz)
{
void *finfo = NULL, *linfo = NULL;
union bpf_attr attr;
void *finfo = NULL;
__u32 name_len;
int fd;
@ -201,6 +226,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
attr.func_info_rec_size = load_attr->func_info_rec_size;
attr.func_info_cnt = load_attr->func_info_cnt;
attr.func_info = ptr_to_u64(load_attr->func_info);
attr.line_info_rec_size = load_attr->line_info_rec_size;
attr.line_info_cnt = load_attr->line_info_cnt;
attr.line_info = ptr_to_u64(load_attr->line_info);
memcpy(attr.prog_name, load_attr->name,
min(name_len, BPF_OBJ_NAME_LEN - 1));
@ -212,36 +240,35 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
* to give user space a hint how to deal with loading failure.
* Check to see whether we can make some changes and load again.
*/
if (errno == E2BIG && attr.func_info_cnt &&
attr.func_info_rec_size < load_attr->func_info_rec_size) {
__u32 actual_rec_size = load_attr->func_info_rec_size;
__u32 expected_rec_size = attr.func_info_rec_size;
__u32 finfo_cnt = load_attr->func_info_cnt;
__u64 finfo_len = actual_rec_size * finfo_cnt;
const void *orecord;
void *nrecord;
int i;
while (errno == E2BIG && (!finfo || !linfo)) {
if (!finfo && attr.func_info_cnt &&
attr.func_info_rec_size < load_attr->func_info_rec_size) {
/* try with corrected func info records */
finfo = alloc_zero_tailing_info(load_attr->func_info,
load_attr->func_info_cnt,
load_attr->func_info_rec_size,
attr.func_info_rec_size);
if (!finfo)
goto done;
finfo = malloc(finfo_len);
if (!finfo)
/* further try with log buffer won't help */
return fd;
attr.func_info = ptr_to_u64(finfo);
attr.func_info_rec_size = load_attr->func_info_rec_size;
} else if (!linfo && attr.line_info_cnt &&
attr.line_info_rec_size <
load_attr->line_info_rec_size) {
linfo = alloc_zero_tailing_info(load_attr->line_info,
load_attr->line_info_cnt,
load_attr->line_info_rec_size,
attr.line_info_rec_size);
if (!linfo)
goto done;
/* zero out bytes kernel does not understand */
orecord = load_attr->func_info;
nrecord = finfo;
for (i = 0; i < load_attr->func_info_cnt; i++) {
memcpy(nrecord, orecord, expected_rec_size);
memset(nrecord + expected_rec_size, 0,
actual_rec_size - expected_rec_size);
orecord += actual_rec_size;
nrecord += actual_rec_size;
attr.line_info = ptr_to_u64(linfo);
attr.line_info_rec_size = load_attr->line_info_rec_size;
} else {
break;
}
/* try with corrected func info records */
attr.func_info = ptr_to_u64(finfo);
attr.func_info_rec_size = load_attr->func_info_rec_size;
fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
if (fd >= 0)
@ -259,6 +286,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
done:
free(finfo);
free(linfo);
return fd;
}

3
tools/lib/bpf/bpf.h
View File

@ -82,6 +82,9 @@ struct bpf_load_program_attr {
__u32 func_info_rec_size;
const void *func_info;
__u32 func_info_cnt;
__u32 line_info_rec_size;
const void *line_info;
__u32 line_info_cnt;
};
/* Flags to direct loading requirements */

211
tools/lib/bpf/btf.c
View File

@ -37,16 +37,26 @@ struct btf {
int fd;
};
struct btf_ext {
void *func_info;
__u32 func_info_rec_size;
__u32 func_info_len;
struct btf_ext_info {
/*
* info points to a deep copy of the individual info section
* (e.g. func_info and line_info) from the .BTF.ext.
* It does not include the __u32 rec_size.
*/
void *info;
__u32 rec_size;
__u32 len;
};
struct btf_sec_func_info {
struct btf_ext {
struct btf_ext_info func_info;
struct btf_ext_info line_info;
};
struct btf_ext_info_sec {
__u32 sec_name_off;
__u32 num_func_info;
/* Followed by num_func_info number of bpf func_info records */
__u32 num_info;
/* Followed by num_info * record_size number of bytes */
__u8 data[0];
};
@ -56,6 +66,14 @@ struct bpf_func_info_min {
__u32 type_id;
};
/* The minimum bpf_line_info checked by the loader */
struct bpf_line_info_min {
__u32 insn_off;
__u32 file_name_off;
__u32 line_off;
__u32 line_col;
};
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
@ -486,12 +504,22 @@ int btf__get_from_id(__u32 id, struct btf **btf)
return err;
}
static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
__u8 *data, __u32 data_size,
btf_print_fn_t err_log)
struct btf_ext_sec_copy_param {
__u32 off;
__u32 len;
__u32 min_rec_size;
struct btf_ext_info *ext_info;
const char *desc;
};
static int btf_ext_copy_info(struct btf_ext *btf_ext,
__u8 *data, __u32 data_size,
struct btf_ext_sec_copy_param *ext_sec,
btf_print_fn_t err_log)
{
const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
const struct btf_sec_func_info *sinfo;
const struct btf_ext_info_sec *sinfo;
struct btf_ext_info *ext_info;
__u32 info_left, record_size;
/* The start of the info sec (including the __u32 record_size). */
const void *info;
@ -500,66 +528,69 @@ static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
data = data + hdr->hdr_len;
data_size -= hdr->hdr_len;
if (hdr->func_info_off & 0x03) {
elog("BTF.ext func_info section is not aligned to 4 bytes\n");
if (ext_sec->off & 0x03) {
elog(".BTF.ext %s section is not aligned to 4 bytes\n",
ext_sec->desc);
return -EINVAL;
}
if (data_size < hdr->func_info_off ||
hdr->func_info_len > data_size - hdr->func_info_off) {
elog("func_info section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
hdr->func_info_off, hdr->func_info_len);
if (data_size < ext_sec->off ||
ext_sec->len > data_size - ext_sec->off) {
elog("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
ext_sec->desc, ext_sec->off, ext_sec->len);
return -EINVAL;
}
info = data + hdr->func_info_off;
info_left = hdr->func_info_len;
info = data + ext_sec->off;
info_left = ext_sec->len;
/* At least a func_info record size */
/* At least a record size */
if (info_left < sizeof(__u32)) {
elog("BTF.ext func_info record size not found");
elog(".BTF.ext %s record size not found\n", ext_sec->desc);
return -EINVAL;
}
/* The record size needs to meet the minimum standard */
record_size = *(__u32 *)info;
if (record_size < sizeof(struct bpf_func_info_min) ||
if (record_size < ext_sec->min_rec_size ||
record_size & 0x03) {
elog("BTF.ext func_info invalid record size");
elog("%s section in .BTF.ext has invalid record size %u\n",
ext_sec->desc, record_size);
return -EINVAL;
}
sinfo = info + sizeof(__u32);
info_left -= sizeof(__u32);
/* If no func_info records, return failure now so .BTF.ext
* won't be used.
*/
/* If no records, return failure now so .BTF.ext won't be used. */
if (!info_left) {
elog("BTF.ext no func info records");
elog("%s section in .BTF.ext has no records", ext_sec->desc);
return -EINVAL;
}
while (info_left) {
unsigned int sec_hdrlen = sizeof(struct btf_sec_func_info);
unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
__u64 total_record_size;
__u32 num_records;
if (info_left < sec_hdrlen) {
elog("BTF.ext func_info header not found");
elog("%s section header is not found in .BTF.ext\n",
ext_sec->desc);
return -EINVAL;
}
num_records = sinfo->num_func_info;
num_records = sinfo->num_info;
if (num_records == 0) {
elog("incorrect BTF.ext num_func_info");
elog("%s section has incorrect num_records in .BTF.ext\n",
ext_sec->desc);
return -EINVAL;
}
total_record_size = sec_hdrlen +
(__u64)num_records * record_size;
if (info_left < total_record_size) {
elog("incorrect BTF.ext num_func_info");
elog("%s section has incorrect num_records in .BTF.ext\n",
ext_sec->desc);
return -EINVAL;
}
@ -567,17 +598,49 @@ static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
sinfo = (void *)sinfo + total_record_size;
}
btf_ext->func_info_len = hdr->func_info_len - sizeof(__u32);
btf_ext->func_info_rec_size = record_size;
btf_ext->func_info = malloc(btf_ext->func_info_len);
if (!btf_ext->func_info)
ext_info = ext_sec->ext_info;
ext_info->len = ext_sec->len - sizeof(__u32);
ext_info->rec_size = record_size;
ext_info->info = malloc(ext_info->len);
if (!ext_info->info)
return -ENOMEM;
memcpy(btf_ext->func_info, info + sizeof(__u32),
btf_ext->func_info_len);
memcpy(ext_info->info, info + sizeof(__u32), ext_info->len);
return 0;
}
static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
__u8 *data, __u32 data_size,
btf_print_fn_t err_log)
{
const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
struct btf_ext_sec_copy_param param = {
.off = hdr->func_info_off,
.len = hdr->func_info_len,
.min_rec_size = sizeof(struct bpf_func_info_min),
.ext_info = &btf_ext->func_info,
.desc = "func_info"
};
return btf_ext_copy_info(btf_ext, data, data_size, &param, err_log);
}
static int btf_ext_copy_line_info(struct btf_ext *btf_ext,
__u8 *data, __u32 data_size,
btf_print_fn_t err_log)
{
const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
struct btf_ext_sec_copy_param param = {
.off = hdr->line_info_off,
.len = hdr->line_info_len,
.min_rec_size = sizeof(struct bpf_line_info_min),
.ext_info = &btf_ext->line_info,
.desc = "line_info",
};
return btf_ext_copy_info(btf_ext, data, data_size, &param, err_log);
}
static int btf_ext_parse_hdr(__u8 *data, __u32 data_size,
btf_print_fn_t err_log)
{
@ -617,7 +680,8 @@ void btf_ext__free(struct btf_ext *btf_ext)
if (!btf_ext)
return;
free(btf_ext->func_info);
free(btf_ext->func_info.info);
free(btf_ext->line_info.info);
free(btf_ext);
}
@ -640,25 +704,32 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
return ERR_PTR(err);
}
err = btf_ext_copy_line_info(btf_ext, data, size, err_log);
if (err) {
btf_ext__free(btf_ext);
return ERR_PTR(err);
}
return btf_ext;
}
int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **func_info, __u32 *cnt)
static int btf_ext_reloc_info(const struct btf *btf,
const struct btf_ext_info *ext_info,
const char *sec_name, __u32 insns_cnt,
void **info, __u32 *cnt)
{
__u32 sec_hdrlen = sizeof(struct btf_sec_func_info);
__u32 i, record_size, existing_flen, records_len;
struct btf_sec_func_info *sinfo;
__u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
__u32 i, record_size, existing_len, records_len;
struct btf_ext_info_sec *sinfo;
const char *info_sec_name;
__u64 remain_len;
void *data;
record_size = btf_ext->func_info_rec_size;
sinfo = btf_ext->func_info;
remain_len = btf_ext->func_info_len;
record_size = ext_info->rec_size;
sinfo = ext_info->info;
remain_len = ext_info->len;
while (remain_len > 0) {
records_len = sinfo->num_func_info * record_size;
records_len = sinfo->num_info * record_size;
info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
if (strcmp(info_sec_name, sec_name)) {
remain_len -= sec_hdrlen + records_len;
@ -666,32 +737,52 @@ int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext,
continue;
}
existing_flen = (*cnt) * record_size;
data = realloc(*func_info, existing_flen + records_len);
existing_len = (*cnt) * record_size;
data = realloc(*info, existing_len + records_len);
if (!data)
return -ENOMEM;
memcpy(data + existing_flen, sinfo->data, records_len);
memcpy(data + existing_len, sinfo->data, records_len);
/* adjust insn_off only, the rest data will be passed
* to the kernel.
*/
for (i = 0; i < sinfo->num_func_info; i++) {
struct bpf_func_info_min *record;
for (i = 0; i < sinfo->num_info; i++) {
__u32 *insn_off;
record = data + existing_flen + i * record_size;
record->insn_off =
record->insn_off / sizeof(struct bpf_insn) +
insn_off = data + existing_len + (i * record_size);
*insn_off = *insn_off / sizeof(struct bpf_insn) +
insns_cnt;
}
*func_info = data;
*cnt += sinfo->num_func_info;
*info = data;
*cnt += sinfo->num_info;
return 0;
}
return -ENOENT;
}
int btf_ext__reloc_func_info(const struct btf *btf, const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **func_info, __u32 *cnt)
{
return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
insns_cnt, func_info, cnt);
}
int btf_ext__reloc_line_info(const struct btf *btf, const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **line_info, __u32 *cnt)
{
return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
insns_cnt, line_info, cnt);
}
__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
{
return btf_ext->func_info_rec_size;
return btf_ext->func_info.rec_size;
}
__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
{
return btf_ext->line_info.rec_size;
}

10
tools/lib/bpf/btf.h
View File

@ -51,6 +51,8 @@ struct btf_ext_header {
/* All offsets are in bytes relative to the end of this header */
__u32 func_info_off;
__u32 func_info_len;
__u32 line_info_off;
__u32 line_info_len;
};
typedef int (*btf_print_fn_t)(const char *, ...)
@ -70,10 +72,16 @@ LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
void btf_ext__free(struct btf_ext *btf_ext);
int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext,
int btf_ext__reloc_func_info(const struct btf *btf,
const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **func_info, __u32 *func_info_len);
int btf_ext__reloc_line_info(const struct btf *btf,
const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **line_info, __u32 *cnt);
__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
#ifdef __cplusplus
} /* extern "C" */

20
tools/lib/bpf/libbpf.c
View File

@ -170,6 +170,10 @@ struct bpf_program {
__u32 func_info_cnt;
struct bpf_capabilities *caps;
void *line_info;
__u32 line_info_rec_size;
__u32 line_info_cnt;
};
struct bpf_map {
@ -1342,6 +1346,19 @@ bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj,
prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext);
}
if (!insn_offset || prog->line_info) {
err = btf_ext__reloc_line_info(obj->btf, obj->btf_ext,
section_name, insn_offset,
&prog->line_info,
&prog->line_info_cnt);
if (err)
return check_btf_ext_reloc_err(prog, err,
prog->line_info,
"bpf_line_info");
prog->line_info_rec_size = btf_ext__line_info_rec_size(obj->btf_ext);
}
if (!insn_offset)
prog->btf_fd = btf__fd(obj->btf);
@ -1526,6 +1543,9 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
load_attr.func_info = prog->func_info;
load_attr.func_info_rec_size = prog->func_info_rec_size;
load_attr.func_info_cnt = prog->func_info_cnt;
load_attr.line_info = prog->line_info;
load_attr.line_info_rec_size = prog->line_info_rec_size;
load_attr.line_info_cnt = prog->line_info_cnt;
if (!load_attr.insns || !load_attr.insns_cnt)
return -EINVAL;